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Hiatal Hernia

What is a Hiatal Hernia?

A hiatal hernia is the abnormal movement of part of the stomach from its normal position in the abdomen into the chest.

The diaphragm is a sheet of muscle which separates the chest and abdomen. The oesophagus (food pipe) and major blood vessels and nerves pass through the diaphragm via small openings within the muscle. During the development of a puppy, these openings may be excessively large, allowing organs which should remain in the abdomen to pass into the chest. The stomach can become permanently displaced but more commonly slides back and forth between the abdomen and the chest.

English Bulldogs are the breed most commonly seen with this condition in the UK. Brachycephalic dogs (those with a shortened nose such as English Bulldogs, French Bulldogs and Pugs) are at an increased risk of displacement of the stomach into the chest as the negative pressures within the chest created by their abnormal airway, act to ‘suck’ the stomach through the opening in the diaphragm.

Dogs with hiatal hernia frequently vomit or regurgitate (passive reflux of stomach contents) due to the abnormal position of the stomach. These signs most commonly occur during peak exercise or when the dog becomes excited. Reflux of acidic stomach contents into the oesophagus results in inflammation (reflux oesophagitis) which can trigger a self-perpetuating cycle of regurgitation causing further inflammation.

Other symptoms which may be observed include excessive salivation, poor appetite and weight loss. Vomiting and/or regurgitation of stomach contents can result in inhalation of this material and the development of secondary pneumonia. In this scenario symptoms such as a cough, nasal discharge and breathing difficulties will be observed.

Hiatal hernia is most commonly diagnosed via fluoroscopy (a moving x-ray study). Whilst the dog is eating, a continuous run of X-rays are taken which allows the swallowing process and position of the stomach to be closely observed. Typical findings consistent with a diagnosis of hiatal hernia are food entering the stomach and then passing back up the oesophagus (reflux) along with movement of the stomach back and forth across the diaphragm.

A fluoroscopy study demonstrating displacement of the stomach into the chest (blue arrows), consistent with a diagnosis of hiatal hernia.

As the stomach typically slides back and forth from a normal to abnormal position, there is the possibility that the imaging study documents a normal stomach position. This does not exclude the diagnosis of hiatal hernia as the most likely explanation for a normal stomach position is that the stomach has not been ‘captured’ in an abnormal position at the time of the imaging study. If this scenario arises, a presumptive diagnosis of hiatal hernia may be made based on the breed of the dog and the symptoms.

The management of hiatal hernia can be broadly divided into medical and surgical options.

Medical management consists of the use of medication to reduce inflammation within the oesophagus (antacids) and aid motility of the gastrointestinal tract. Medication often reduces the severity and frequency of the symptoms but is unlikely to eliminate them completely due to the persistently abnormal position of the stomach.

Surgical correction is often indicated to resolve the clinical problems. In some patients surgical correction of the upper airway problems, as seen in Brachycephalic dogs, eliminates the problems. In other patients the surgery will consist of reducing the size of the overly large opening in the diaphragm and stitching the oesophagus and stomach permanently in a normal position. This technique prevents movement of the stomach into the chest.

The prognosis following surgery is good. The aim is to eliminate the symptoms (regurgitation and vomiting) completely. Rarely, dogs may continue to regurgitate and/or vomit after surgery although with a markedly reduced frequency compared to before surgery. If this is the case, these mild symptoms can usually be controlled with the use of medication.